As Europe accelerates its ambitions to achieve climate neutrality by 2050, the energy system is set to look very different from the one we see today. Driven by ambitious climate targets, the electricity sector especially is taking great strides in reducing greenhouse gas emissions by replacing fossil fuel generators with renewables. However, the inherent variability of wind and solar generation brings with it new challenges. The electricity system needs to become much more flexible than it is today to accommodate the rising share of renewables and new flows of electricity that come with it. Variable production of wind and solar means renewable deployment alone will not eliminate fossil fuel dependence, as backup gas generators are used to cover renewables energy shortfalls at times of low production. If the EU is to meet its climate targets in time and integrate even higher shares of renewables as stated in the REPowerEU plan, reliance on fossil fuel imports and backup gas generation must be replaced with alternative low emission solutions.

Energy shifting and flexibility services provided by energy storage are indispensable for system reliability and securing supply of energy to cope with moments of low renewables and also maximise renewable utilisation at times of high production. While flexibility services can also be provided by other technologies, energy storage is the only solution able to provide the essential energy shifting service which is one of the key solutions to minimising curtailment of renewable energy. This will ensure a self-sufficient European energy economy by maximising utilisation of local renewables, reducing reliance on external fossil fuel imports, in turn alleviating the high electricity prices seen today.

REPowerEU clearly acknowledges this and the important role of energy storage to reduce the use of gas power plants in the energy system [1]. It is therefore critical that the role of greenhouse gas (GHG) emitting flexibility from fossil fuel generators is reconsidered especially by 2030*.

However, storage uptake today is seriously lagging behind wind and solar deployment. The EU risks being unable to integrate the rapidly growing renewables and in turn being locked into fossil fuel backup, if storage deployment does not go in parallel with renewable uptake. With this paper we assess the energy storage requirements as a whole for Europe and propose estimates of energy storage targets for 2030 and 2050 based on a review of existing scientific literature, official documents from the European Commission (EC) and input from relevant stakeholders. We find that many studies do not address all key energy storage technologies and durations, often undervaluing low emission technologies and energy shifting resources and overvaluing the use of GHG emitting baseload plants especially in the 2030 time horizon [2]. Many studies are based on outdated climate targets which leads to an underestimation of flexibility needs in the energy system. Furthermore, the rapidly changing storage technology and innovation landscape means new cost projections need to be included in energy system planning today to accurately reflect technologies available [3] [4].